Showing papers on "Breakwater published in 2013"

On Design and Building of a U-OWC Wave Energy Converter in the Mediterranean Sea: A Case Study

Abstract: Since the nineties, the OWC (Oscillating Water Column) plants were developed at full scale to produce electrical power from ocean waves [1]. A prototype was built into a caisson breakwater of the Sakata Port, in Japan; other plants were built in India, in Scotland at Islay, in Portugal at the Azores. A new plant was built in Mutriku (Spain) recently. A new kind of OWC caisson, named U-OWC or REWEC3, was proposed by Boccotti [2]. With respect to a traditional OWC, a U-OWC plant includes an additional vertical duct, which enables to tune the eigenperiod of the plant to the peak period of the wave pressures acting on the converter-breakwater. In this way, resonance conditions can be reached without phase control devices and the wave pressures into the air pocket are increased in amplitude, amplifying the performance of the plant. In 2012, a full scale U-OWC (REWEC3) breakwater has been designed in Italy, for the harbour of Civitavecchia (the port of Rome – Port Authority of Civitavecchia). Such a breakwater embodies 19 caissons, each including 8 cells, 34m long. The paper disseminates the key issues pertaining the design stage. Further, it describes the main phases of the construction stage. The building of the caisson started in October 2012. The first caisson has been completed at the end of 2012. It is the first device for wave energy in the Mediterranean Sea and one of the biggest in the world.Copyright © 2013 by ASME

Design and Construction of Mounds for Breakwaters and Coastal Protection

Abstract: 1. Introduction. 2. Basic Parameters for Design. 3. Design. 4. Construction. 5. Examples of Mound Breakwaters including Some Breakdowns. 6. All-Over Conclusion. 7. Coastal Protective Mounds and Revetments. 8. Alternative Designs of Mounds, Bituminous Structures. Index.

Wave loadings acting on Overtopping Breakwater for Energy Conversion

Abstract: Vicinanza, D., Norgaard, J.H., Contestabile, P. and Andersen, T.L., 2013. Wave loadings acting on Overtopping BReakwater for Energy Conversion. Any kind of Wave Energy Converter (WEC) requires information on reliability of technology and on time required for the return of the investment (reasonable payback). The structural response is one of the most important parameters to take in to account for a consistent assessment on innovative devices. This paper presents results on wave loading acting on an hybrid WEC named Overtopping BReakwater for Energy Conversion (OBREC). The new design is based on the concept of an integration between a traditional rubble mound breakwater and a front reservoir designed to store the wave overtopping from the incoming wave to produce electricity. 2D hydraulic model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark). The analyses of hydraulic model tests have identified the main shapes assumed by wave surfaces at the breakwater ...

Storm-induced readjustment of an embayed beach after modification by protection works

Abstract: This paper examines storm-induced morphological and hydrodynamic changes after a submerged and a detached breakwater were constructed at La Barceloneta beach (Barcelona, NW Mediterranean) in 2006–2007. The shoreline configurations before and after beach nourishment and the construction of the protective structures were compared using a video dataset comprising 29 storm events spanning the pre- (2001 to 2005, n = 17) and the post-breakwater situation (2006 to 2011, n = 12), and hydrodynamic modelling based on the SMC coastal modelling system. As a result of the protection works, La Barceloneta was subdivided into two beaches separated by an artificial salient. The analysis of shoreline response to storms has been improved by using the shoreline hyperbolic tangent fit to represent the beach planform. Comparing the pre- and post-breakwater situations on the basis of these shoreline fits facilitated the identification of beach rotation processes because interference by smaller-scale morphological features was eliminated (e.g. the formation, changes in shape or migration of mega-cusps). In the current post-breakwater situation, there is evidence for a change in the behaviour of the north-eastern beach triggered by the submerged breakwater built in 2007. Furthermore, a counter-clockwise beach rotation has occurred at the north-eastern beach, whereas the south-western beach has experienced a clockwise beach rotation. This morphodynamic behaviour is caused by a new, complex wave-induced circulation system comprising two dominant alongshore currents flowing in opposite directions. In contrast to the pre-breakwater situation, the alongshore component of the radiation stress does not accomplish beach rotation in the post-breakwater situation.

Shoreline behind a Breakwater: Comparison between Theoretical Models and Field Measurements for the Reggio Calabria Sea

Abstract: Barbaro, G. and Foti, G., 2013. Shoreline behind a breakwater: comparison between theoretical models and field measurements for the Reggio Calabria Sea. Longshore sediment transport is affected by coastal structures, which cause phenomena such as the erosion and deposition of sediments. These phenomena may also occur at locations far from the coastal structure. The prediction and management of shoreline evolution are necessary to protect coasts; they should take into account both long-term and short-term effects and should consider the presence or absence of coastal structures. In this paper several models that predict shoreline evolution behind a breakwater have been analyzed. The results of the predictions have been compared with real shoreline evolution measured in the Natural Ocean Engineering Laboratory (NOEL) in Reggio Calabria, where an experiment concerning the possibility of converting wave energy into electricity using a particular device placed in a breakwater is being investigated. A ...

Long-Term Modelling of Wave Run-Up and Overtopping during Sea Storms

Abstract: Arena, F.; Malara, G.; Barbaro, G.; Romolo, A., and Ghiretti, S., 2013. Long-term modelling of wave run-up and overtopping during sea storms. This paper is concerned with the determination of the return period of a sea storm in which response (run-up or overtopping) of a coastal structure exceeds a fixed threshold. The method is based on long-term statistical analysis of the sea states interacting with the structure and on practical formulas proposed in the past decades for determining response of coastal structures. The proposed methodology accounts for nonstationarity of sea states in time domain by the equivalent triangular storm model, which allows us to determine closed-form solutions of the return period of a storm where maximum significant wave height is larger than a fixed threshold. In this paper the analytical solution is supplemented by a practical application pertaining calculation of the response of a coastal structure. A rubble-mound breakwater is supposed to be placed at a known wa...

Hydraulic performance of free surface breakwaters: a Review

Abstract: This paper introduces the concept of free surface breakwaters for coastal protection. The advantages, limitations and applications of these breakwaters are discussed. Based on their configurations, free surface breakwaters have been classified into four types, namely solid-type, plate-type, caisson-type and multipart-type. Typical designs of the respective breakwater types are presented and the hydraulic characteristics are reviewed. In addition, comparisons of hydraulic efficiency of some of the free surface breakwaters are also addressed in this paper.

Experimental and Numerical Investigation on Wave Interaction with Submerged Breakwater

Abstract: Experimental studies are carried out in a two-dimensional wave flume (21.3 m long, 0.76 m wide and 0.74 m deep) to investigate the performance of rectangular type submerged breakwater. A set of experiments are carried out at 50 cm still water depth with fixed submerged breakwaters of three different heights (30 cm, 35 cm and 40 cm) for five different wave periods (1.5 sec, 1.6 sec, 1.7 sec, 1.8 sec and 2.0 sec) in the same wave flume. For fifteen run conditions, water surface elevations are collected at six different locations both in front of and behind the breakwater. Also the type of wave breaking and position of wave breaking are simultaneously recorded with a digital video camera. Effects of breakwater height and length along the wave direction on wave height reduction are analyzed. It is found that both the relative structure height (hs/h) and relative breakwater width (B/L) have strong influence in reducing transmitted wave height. Experimental analysis prevails that the reduction of transmitted wave height are 50%, 58% and 68% for relative structure height (hs/h) of 0.6, 0.7 and 0.8 respectively, for a particular value of relative breakwater width (B/L =0.35). Also, the reduction of transmitted wave height is 32% and 50% for relative breakwater width (B/L) of 0.25 and 0.4 respectively, for a particular value of relative structure height (hs/h =0.6). A two-dimensional numerical model based on the SOLA-VOF method has been developed in this study to investigate the wave interaction with fixed submerged breakwater. The developed model can simulate time series water surface profiles, water particle velocity field, VOF function F, pressure around a breakwater. The water surface profiles and wave breaking positions in various wave conditions simulated by the developed numerical model show good agreement with the experimentally measured values. The numerical model developed in this study is expected to serve as tool to analyze wave deformation due to submerged breakwater and will be important for designing submerged breakwater as a coastal protection measure.

3D numerical model for wave-induced seabed response around breakwater heads

Abstract: This paper presents a three-dimensional (3D) integrated numerical model where the wave-induced pore pressures in a porous seabed around breakwater heads were investigated. Unlike previous research, the Navier-Stokes equation is solved with internal wave generation for the flow model, while Biot's dynamic seabed behaviour is considered in the seabed model. With the present model, a parametric study was conducted to examine the effects of wave and soil characteristics and breakwater configuration on the wave-induced pore pressure around breakwater heads. Based on numerical examples, it was found that the wave-induced pore pressures at breakwater heads are greater than that beneath a breakwater. The wave-induced seabed response around breakwater heads become more important with: (i) a longer wave period; (ii) a seabed with higher permeability and degree of saturation; and (iii) larger angle between the incident waves and breakwater. Furthermore, the relative difference of wave-induced pore pressure between fully-dynamic and quasi-static solutions are larger at breakwater heads than that beneath a breakwater.

Front slope stability of the icelandic-type berm breakwater

Abstract: acceptance number: p0112 FRONT SLOPE STABILITY OF THE ICELANDIC-TYPE BERM BREAKWATER 1 Author: Sigurdarson, Sigurdur 2 Author: van der Meer, Jentsje Breakwaters Berm Breakwaters Coastal structures Icelandic-type Recession Stable berm breakwater

Hydrodynamic performance of a composite breakwater with an upper horizontal porous plate and a lower rubble mound

Abstract: A composite breakwater with an upper horizontal porous plate and a lower rubble mound is proposed and studied in this work. By means of matched eigenfunction expansions, a semi-analytical solution is developed for analyzing the hydrodynamic performance of the breakwater. The semi-analytical solution is verified by known solutions for special cases and an independently developed multi-domain boundary element method solution. Numerical examples are given to examine the reflection, transmission and energy loss coefficients of the breakwater and the wave force acting on the horizontal porous plate. Some useful results are presented for engineering applications.

Predicting wave transmission past Reef Ball™ submerged breakwaters

Abstract: Buccino, M., Del Vita, I., and Calabrese, M., 2013. Predicting wave transmission past Reef BallTM submerged breakwaters Reef Balls™ are hemispherical shaped artificial units, made of neutral concrete and characterized by a particular surface textures to promote the growth of marine life. They can be arranged in different layouts to form submerged breakwaters, even of significant width. Although structures in Reef Balls have been employed for the protection of a number of top quality sites, no well-established design tool exists for the prediction of wave transmission behind them. In this article a set of equations is provided, based on the so-called “Conceptual Approach” originally developed for ordinary structures. The new expressions proved to fit properly more than 300 experimental data, coming from physical model tests conducted at two different American laboratories: Queen's University Coastal Engineering Research Laboratory (Canada) and the USACE Engineering Research and Development Center ...

Analysis, evaluation and innovative methodologies to prevent coastal erosion

Abstract: The main characteristic of a coastal system is its variability. Many factors are involved in the evolution of the shoreline, which can depend on the weather, on geology, and on the presence or absence of river mouths. They can also depend on the urbanization of the coasts or of the interior areas. In order to prevent coastal erosion, it is necessary to clearly understand the interaction of so many factors. In this regard both geological and historical aspects, experimental and theoretical models have to be considered in order to analyze the extreme variability of the system. This paper is divided into three parts. The first is concerned with the historical variation of the Calabria shoreline, evaluated through cartographic analysis. All data are provided by the Calabria Basin Authority and the analysis is made with GIS software. The first part ends with the identification of the areas characterized by coastal erosion. The second part is concerned with the evaluation of the causes of the erosion and the identification of the best type of intervention. The last part is concerned with the latest approaches to coastal dynamic, in particular Barbaro et al. (“Set-up due to random waves: influence of the directional spectrum”, Proc. of the 30 th Int. Conf. on Ocean, Offshore and Artic Eng., Rotterdam, 2011 and “A probabilistic approach for the run-up estimation”, Proc. of the 5 th Int. Short Conf. on Appl. Coastal Res., Aachen, 2011) to evaluate the set-up and the run-up, Tomasicchio et al. (“A general longshore transport model. Coastal Eng., 71, pp. 28–36, 2013), to evaluate the total longshore transport rate and Barbaro and Foti, “Shoreline behind a breakwater: comparison between theoretical models and field measurements for

Practical Methods of Estimating Tilting Failure of Caisson Breakwaters Using a Monte-Carlo Simulation

Abstract: The authors propose a new method to estimate the tilting failure of caisson breakwaters, using a Monte-Carlo simulation that can quantitatively and stochastically estimate failure probability. An i...